Phase difference film, polaroid and display device

Abstract

The invention relates to a phase difference film, a polaroid and a display device. The phase difference film satisfies optical characteristics represented by formula (1) or formula (2): Rth (450) / Rth (550) > 2 (1); rth (450) / Rth (550) is less than-1 (2); in the formula, Rth (450) represents a phase difference in the thickness direction at a wavelength of 450 nm, and Rth (550) represents a phase difference in the thickness direction at a wavelength of 550 nm. By adjusting the relationship between the phase differences of the phase difference film in the thickness direction under different wavelengths, when the phase difference film is applied to the display device, the problem that the side view dark state is yellowish can be solved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a phase difference film, a polarizing plate and a display device. Background Art

[0002] Thin Film Transistor Liquid Crystal Display (TFT-LCD) with wide viewing angle and high display quality has become the mainstream display product on the market. Among them, TFT-LCD in Fringe Field Switching (FFS) and In-Plane Switching (IPS) mode has been widely used as display panels for portable mobile communication devices such as mobile phones and tablet computers due to its fast response, wide viewing angle and low power consumption.

[0003] However, FFS / IPS mode liquid crystal displays have a yellowish color problem in the dark state, which reduces the image display quality of the display. Summary of the invention

[0004] The embodiments of the present application provide a phase difference film, a polarizer and a display device, which can at least effectively improve the side-view dark state yellowing problem of the display device using the phase difference film, thereby facilitating improving the display quality of the display device.

[0005] In order to achieve the above object, according to the first aspect of the present application, a phase difference film is provided, wherein the phase difference film satisfies the optical properties represented by formula (1) or formula (2):

[0006] Rth(450) / Rth(550)>2 (1);

[0007] Rth(450) / Rth(550)<-1 (2);

[0008] Wherein, Rth(450) represents the phase difference in the thickness direction at a wavelength of 450 nanometers, and Rth(550) represents the phase difference in the thickness direction at a wavelength of 550 nanometers.

[0009] In some embodiments, the phase difference film further satisfies the optical properties expressed by formula (3) to formula (6):

[0010] -10nm<Ro(450)<15nm (3);

[0011] -20nm<Rth(450)<10nm (4);

[0012] -20nm<Rth(550)<20nm (5);

[0013] -20nm<Rth(650)<20nm (6);

[0014] In the formula, Ro(450) represents the in-plane phase difference at a wavelength of 450 nanometers, and Rth(650) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 650 nanometers.

[0015] In some embodiments, the phase difference film further satisfies the optical properties expressed by the formula (1) and the following formulas (7) and (8):

[0016] 0<Rth(450)<Rth(550)<Rth(650) (7);

[0017] 2nm<Ro(450)<15nm (8).

[0018] In some embodiments, the phase difference film further satisfies the optical properties expressed by the formula (2) and the following formula (9):

[0019] Rth(450)<0<Rth(550)<Rth(650) (9).

[0020] In some embodiments, the phase difference film further satisfies the optical properties expressed by formula (10), formula (11) and formula (12):

[0021] Rth(450)<0<Rth(650)<Rth(550) (10);

[0022] Rth(450) / Rth(550)<-1.5 (11);

[0023] -2.5nm<Ro(450)<15nm (12).

[0024] In some embodiments, the material of the phase difference film further includes a phase difference adjusting agent, and the phase difference adjusting agent is selected from at least one of polyurethane, polyvinyl chloride, chlorinated polyvinyl chloride, polypropylene, chlorinated polypropylene and polyethylene.

[0025] In some embodiments, the material of the phase difference film further includes a substrate, and the substrate is selected from polymethyl methacrylate or triacetyl cellulose.

[0026] In some embodiments, in the material of the phase difference film, when the weight proportion of the phase difference film is 100 parts, the weight proportion of the substrate is greater than or equal to 90 parts and less than 100 parts, and the weight proportion of the phase difference adjuster is greater than or equal to 0.9 parts and less than or equal to 7.5 parts.

[0027] According to the second aspect of the present application, a polarizer is also provided, comprising a polarizing layer, a protective layer and the phase difference film mentioned above, wherein the phase difference film is located on a side of the polarizing layer away from the protective layer.

[0028] According to a third aspect of the present application, a display device is further provided, comprising a display module and the polarizer described above, wherein the polarizer is at least located on a light-emitting side of the display module.

[0029] In the phase difference film, polarizer and display device of the embodiments of the present application, by making the phase difference Rth in the thickness direction of the phase difference film satisfy the optical properties represented by formula (1) or formula (2), when the phase difference film is applied to a display device, especially a liquid crystal display device in FFS and IPS modes, the side-view dark state yellowing of the display device can be improved, which is beneficial to improving the display quality of the display device.

[0030] Other features and advantages of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0032] In order to more completely understand the present application and its beneficial effects, the following description will be given in conjunction with the accompanying drawings, wherein the same figure numbers represent the same parts in the following description.

[0033] Figure 1a to Figure 1d They are full-viewing angle brightness diagrams of the liquid crystal display devices corresponding to the experimental group 1, the experimental group 2, the experimental group 3 and the control group of the embodiment of the present application;

[0034] Figure 2 It is a schematic flow chart of a method for preparing a phase difference film provided in an embodiment of the present application;

[0035] Figure 3 is a schematic structural diagram of a polarizer provided in an embodiment of the present application;

[0036] Figure 4 It is a structural schematic diagram of a display device provided in an embodiment of the present application.

[0037] Reference numerals: 1. polarizer; 2. polarizing layer; 3. protective layer; 4. phase difference film; 5. pressure-sensitive adhesive layer; 6. release film; 7. removable protective film; 8. display module; 9. light-emitting side; 10. display device. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0039] The embodiment of the present application provides a phase difference film, which at least satisfies the optical properties represented by formula (1) or formula (2):

[0040] Rth(450) / Rth(550)>2 (1);

[0041] Rth(450) / Rth(550)<-1 (2);

[0042] In the formula, Rth(450) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 450 nanometers, and Rth(550) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 550 nanometers.

[0043] In some embodiments, the phase difference film further satisfies the optical properties expressed by formula (3) to formula (6):

[0044] -10nm<Ro(450)<15nm (3);

[0045] -20nm<Rth(450)<10nm (4);

[0046] -20nm<Rth(550)<20nm (5);

[0047] -20nm<Rth(650)<20nm (6);

[0048] In the formula, Ro(450) represents the in-plane phase difference at a wavelength of 450 nanometers, and Rth(650) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 650 nanometers.

[0049] Specifically, the in-plane phase difference (Ro) and the thickness direction phase difference (Rth) are defined by equation (A) and equation (B), respectively:

[0050] Ro=(nx-ny)×d ( A);

[0051]

[0052] Wherein, nx, ny and nz represent the refractive index of the phase difference film in the x-axis direction, y-axis direction and z-axis direction at each measurement wavelength, respectively, and d is the thickness of the phase difference film (unit: nanometer).

[0053] It is understood that the phase difference film described in the embodiment of the present application refers to an optical film having a specific optical function of imparting a phase difference to the transmitted light. The in-plane phase difference (Ro) and the phase difference in the thickness direction (Rth) can be measured using an automatic birefringence meter, but are not limited thereto.

[0054] Applying the above-mentioned phase difference film to the polarizer of the display device is beneficial to improving the dark state yellowing problem of the display device, especially to improving the dark state yellowing and light leakage problems of FFS / IPS mode liquid crystal displays.

[0055] In a specific embodiment, the phase difference film further satisfies the optical properties represented by formula (1), formula (7) and formula (8) on the basis of satisfying the optical properties represented by formula (3) to formula (6):

[0056] Rth(450) / Rth(550)>2 (1);

[0057] 0<Rth(450)<Rth(550)<Rth(650) (7);

[0058] 2nm<Ro(450)<15nm (8).

[0059] Specifically, when the phase difference film satisfies the optical properties expressed by formula (1), formula (7) and formula (8), the phase difference film is applied to the polarizer of the display device, which can effectively improve the dark state yellowing problem of the display device, especially for the dark state yellowing and light leakage problems of FFS / IPS mode liquid crystal displays.

[0060] In another specific embodiment, the phase difference film further satisfies the optical properties represented by formula (2) and formula (9) on the basis of satisfying the optical properties represented by formula (3) to formula (6):

[0061] Rth(450) / Rth(550)<-1 (2);

[0062] Rth(450)<0<Rth(550)<Rth(650) (9).

[0063] Specifically, when the phase difference film satisfies the optical properties expressed by formula (2) and formula (9), applying the phase difference film to the polarizer of a display device can also effectively improve the dark state yellowing problem of the display device, especially for the dark state yellowing and light leakage problems of FFS / IPS mode liquid crystal displays.

[0064] In another specific embodiment, the phase difference film further satisfies the optical properties represented by formula (10), formula (11) and formula (12) on the basis of satisfying the optical properties represented by formula (3) to formula (6):

[0065] Rth(450)<0<Rth(650)<Rth(550) (10);

[0066] Rth(450) / Rth(550)<-1.5 (11);

[0067] -2.5nm<Ro(450)<15nm (12).

[0068] Specifically, when the phase difference film satisfies the optical properties expressed by formula (10), formula (11) and formula (12), applying the phase difference film to the polarizer of a display device can also effectively improve the dark state yellowing problem of the display device, especially for the dark state yellowing and light leakage problems of FFS / IPS mode liquid crystal displays.

[0069] Specifically, the optical properties of the phase difference film can meet the above requirements by adjusting the material and thickness.

[0070] In some embodiments, the material of the phase difference film includes a substrate, and the substrate is selected from polymethyl methacrylate (PMMA) or triacetate cellulose (TAC).

[0071] In a preferred embodiment, the substrate of the phase difference film is selected from PMMA. Since the moisture resistance / moisture permeability coefficient of PMMA is better than that of TAC, using PMMA as the substrate of the phase difference film in the display device can improve the reliability of the phase difference film, making the phase difference film less affected by temperature and humidity, and not easily causing the image quality of the display device to deteriorate.

[0072] In some embodiments, the material of the phase difference film further includes a phase difference adjusting agent and an ultraviolet light absorber. Specifically, the phase difference adjusting agent is used to adjust the phase difference so that the in-plane phase difference (Ro) and the phase difference in the thickness direction (Rth) meet the requirements of optical properties; the ultraviolet light absorber is used to absorb ultraviolet light.

[0073] In a specific embodiment, the phase difference adjusting agent is selected from at least one of polyurethane, polyvinyl chloride, chlorinated polyvinyl chloride, polypropylene, chlorinated polypropylene and low molecular weight polyethylene. Considering the compatibility and processability of the materials, the phase difference adjusting agent added to the above substrate usually does not exceed three materials.

[0074] It should be noted that the phase difference adjusting agent used in the embodiment of the present application has good compatibility with PMMA, which is beneficial to improving the processability (such as heat resistance) of the phase difference film of the PMMA substrate, thereby solving the problem that the film made when PMMA is used to prepare the phase difference film is brittle and difficult to process.

[0075] In a specific embodiment, the ultraviolet light absorber is selected from triazine organic compounds, such as 2,4,6-tris(2'-n-butoxyphenyl)-1,3,5-triazine.

[0076] In some embodiments, when the weight proportion of the phase difference film is 100 parts, the weight proportion of the substrate is greater than or equal to 90 parts and less than 100 parts, the weight proportion of the phase difference adjusting agent is greater than or equal to 0.9 parts and less than or equal to 7.5 parts, and the weight proportion of the ultraviolet light absorber is greater than or equal to 0.5 parts and less than or equal to 4 parts.

[0077] In some embodiments, the material of the phase difference film further includes a plasticizer and an antioxidant, and the present embodiment of the application does not limit the materials of the plasticizer and the antioxidant. When the weight proportion of the substrate is 100 parts, the weight proportion of the plasticizer is 0.1 to 0.8 parts, and the weight proportion of the antioxidant is 0.02 to 0.2 parts.

[0078] In some embodiments, the material of the plasticizer is selected from dipropylene glycol dibenzoate with a molecular weight of 342, but is not limited thereto.

[0079] In some embodiments, the material of the antioxidant is selected from N,N′-bis-(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine (Antioxidant 1098), but is not limited thereto.

[0080] Of course, in other embodiments, the material of the phase difference film may further include other additives, which are not limited here.

[0081] In a specific embodiment, the material of the phase difference film consists of 95 parts of PMMA, 4.5 parts of polyurethane and 2.1 parts of 2,4,6-tris(2'-n-butoxyphenyl)-1,3,5-triazine, and the phase difference film satisfies the optical properties represented by formula (2) and formula (9).

[0082] In another specific embodiment, the material of the phase difference film consists of 95 parts of PMMA, 5.2 parts of polyurethane and 2.1 parts of 2,4,6-tris(2'-n-butoxyphenyl)-1,3,5-triazine, and the phase difference film satisfies the optical properties represented by formula (1), formula (7) and formula (8).

[0083] In another specific embodiment, the material of the phase difference film is composed of 95 parts of PMMA, 4.1% of polyurethane, 2.1 parts of 2,4,6-tris(2'-n-butoxyphenyl)-1,3,5-triazine, 0.4 parts of dipropylene glycol dibenzoate and 0.07% (by weight) of antioxidant 1098, and the phase difference film satisfies the optical properties expressed by formula (10), formula (11) and formula (12).

[0084] In order to verify that the phase difference film provided in the embodiment of the present application can improve the problems of yellowish display and light leakage when applied to the display, the embodiment of the present application provides three phase difference films composed of different materials as experimental group 1, experimental group 2 and experimental group 3, and provides a control phase difference film as a control group for testing and verification, wherein the phase difference films provided by experimental group 1, experimental group 2 and experimental group 3 are the phase difference films described in the embodiment of the present application, and the control phase difference film provided by the control group is different from the material composition and optical properties of the phase difference film to be protected by the embodiment of the present application.

[0085] Specifically, the material composition and ratio (weight ratio) of the phase difference films provided by experimental group 1, experimental group 2 and experimental group 3 and the control phase difference film provided by the control group are shown in Table 1. As can be seen from Table 1, the difference between experimental group 1 and experimental group 2 is that the type and ratio of the phase modifier in the phase difference film are different; the difference between experimental group 3 and experimental group 2 is that the material and ratio of the substrate in the phase difference film and the ratio of the phase modifier are different, and the difference between experimental group 3 and experimental group 1 and experimental group 2 is that the material of the phase difference film of experimental group 3 also includes a plasticizer and an antioxidant; the control phase difference film provided by the control group does not contain a phase difference modifier.

[0086] The inventors measured the transmittance, haze, thickness, Ro(450), Rth(450), Rth(550) and Rth(650) of the phase difference films provided by the experimental groups 1, 2 and 3 and the control phase difference films provided by the control group, and the results are shown in Table 2. As can be seen from Table 2, the transmittance of the phase difference films provided by the experimental groups 1, 2 and 3 of the present application is greater than 90%, and the haze is greater than or equal to 0.4, indicating that these phase difference films have good optical properties (high transmittance and low haze).

[0087] Table 1

[0088]

[0089] Furthermore, it can be seen from Table 2 that the phase difference film provided by the experimental group 1 of the present application satisfies the optical properties expressed by formula (2) and formula (9), the phase difference film provided by the experimental group 2 of the present application satisfies the optical properties expressed by formula (1), formula (7) and formula (8), and the phase difference film provided by the experimental group 3 of the present application satisfies the optical properties expressed by formula (10), formula (11) and formula (12); while Ro (450), Rth (450), Rth (550) and Rth (650) of the control phase difference film provided by the control group do not satisfy the optical properties expressed by formulas (1) to (12).

[0090] Table 2

[0091]

[0092] It can be understood that the difference between the phase difference films provided by experimental groups 1, 2 and 3 and the control phase difference film provided by the control group lies in the difference in Ro / Rth curve caused by whether a phase difference adjuster is used and the difference in materials and proportions of the phase difference adjuster, and the optical properties of the phase difference film are changed by the difference in Ro / Rth curve.

[0093] The phase difference films provided by experimental group 1, experimental group 2 and experimental group 3 and the control phase difference film provided by the control group were respectively applied to FFS type liquid crystal display devices, and the full viewing angle brightness graphs of each liquid crystal display device were obtained by optical viewing angle detector (ELDIM) test. Of course, the full viewing angle brightness graphs of each liquid crystal display device can also be obtained by simulation through Tech Wiz software, which is not limited in this application.

[0094] The full viewing angle brightness diagrams of the liquid crystal display devices corresponding to the experimental group 1, the experimental group 2, the experimental group 3 and the control group are shown as follows: Figure 1a , Figure 1b , Figure 1c and Figure 1d As shown, according to Figure 1a , Figure 1b , Figure 1c and Figure 1d The full-viewing angle brightness diagram shown can obtain the values ​​of the color coordinates x and y of the liquid crystal display devices provided by experimental group 1, experimental group 2, experimental group 3 and control group at the coordinates (45°, 60°) and (135°, 60°), and the results are shown in Table 2.

[0095] It should be noted that the positions represented by the coordinates (45°, 60°) and (135°, 60°) in the full-viewing angle luminance diagram represent the side-viewing angle positions.

[0096] Depend on Figure 1dAs shown in Table 2, the control phase difference film provided by the control group has Ro and Rth values ​​outside the protection scope of the present application. When the control phase difference film is applied to a liquid crystal display device, it exhibits a higher color coordinate x or y value at the coordinates (45°, 60°) and (135°, 60°), resulting in a slightly yellowish color cast. In other words, when the control phase difference film provided by the control group is applied to a liquid crystal display device, a yellowish color cast will occur when viewed from the side.

[0097] And by Figure 1a , Figure 1b , Figure 1c As can be seen from Table 2, compared with the control group, when the phase difference film provided by Experimental Group 1, Experimental Group 2 and Experimental Group 3 of the present application is applied to a liquid crystal display device, the color coordinate x or y value at the coordinates (45°, 60°) and (135°, 60°) is reduced, indicating that the phase difference film provided in the embodiment of the present application is beneficial to reducing the problem of yellowish side view when applied to a liquid crystal display device.

[0098] It should be noted that the above color coordinates are color coordinates under the CIE 1931 coordinate system, and the liquid crystal display panel used for the test is a liquid crystal display panel in a fringe field switching (FFS) mode.

[0099] And, according to Figure 1a , Figure 1b , Figure 1c and Figure 1d The full-viewing angle brightness diagram shown can obtain the brightness values ​​of the liquid crystal display devices provided by experimental group 1, experimental group 2, experimental group 3 and control group at coordinates (45°, 60°) and (135°, 60°), and the results are shown in Table 2.

[0100] It can be seen from Table 2 that compared with the control group, when the phase difference film provided by Experimental Group 1, Experimental Group 2 and Experimental Group 3 of the present application is applied to the liquid crystal display device, the brightness Lv at the coordinates (45°, 60°) and (135°, 60°) is reduced, which shows that the phase difference film provided in the embodiment of the present application is beneficial to reducing light leakage when applied to the liquid crystal display device.

[0101] It should be noted that although the above verification experiment uses an FFS mode liquid crystal display panel, according to the inventor's research, the phase difference film provided in the embodiment of the present application can also effectively improve the side view yellowing and light leakage problems of the IPS mode liquid crystal display panel.

[0102] As can be seen from the above, the phase difference film provided in the embodiment of the present application can be used to improve the side-view dark state yellowing problem of the display device, especially the FFS mode and IPS mode liquid crystal display device (i.e., reduce the oblique horizontal yellow color shift problem when displaying black), and can also reduce the light leakage of the display device, thereby improving the display quality of the display device. In addition, the phase difference film provided in the embodiment of the present application has excellent heat resistance and optical properties (light transmittance>90%), and has low haze and is not easy to break.

[0103] like Figure 2 As shown, the embodiment of the present application further provides a method for preparing the phase difference film described in the above embodiment, and the preparation method includes steps S201 and S202.

[0104] S201: mixing a substrate, a phase difference adjusting agent and an ultraviolet light absorber in a preset weight ratio, and preparing an initial phase difference film with a first thickness by an extrusion molding method or a solution casting method.

[0105] It should be noted that the initial phase difference film prepared in step S201 is an unstretched phase difference film.

[0106] Taking the extrusion molding method as an example, step S201 includes the following process:

[0107] A base material (such as polymethyl methacrylate (PMMA)), a phase difference adjusting agent (also referred to as a modified monomer), and an ultraviolet light absorber are mixed in a preset weight ratio, and the mixture is compounded in a twin-screw extruder to prepare a resin composition;

[0108] The resin composition was melted at 250° C. and extruded in a sheet form through a T-die, a casting roll, and a drying roll to obtain an initial phase difference film of a first thickness.

[0109] In a specific embodiment, the first thickness is 80 micrometers (um), but is not limited thereto.

[0110] It is understood that the substrate can also be selected from triacetyl cellulose TAC.

[0111] Specifically, the preset weight ratio can refer to the description of the weight ratio of the substrate, the phase difference adjusting agent and the ultraviolet light absorber in the above-mentioned embodiment, which will not be repeated here.

[0112] S202: stretching the initial phase difference film to form the phase difference film having a second thickness; the second thickness is smaller than the first thickness.

[0113] It should be noted that step S201 is a stretching treatment of the initial phase difference film prepared in step S201. The stretching method includes but is not limited to biaxial stretching, free width uniaxial stretching or fixed width uniaxial stretching, wherein the biaxial stretching method is superior to the uniaxial stretching method.

[0114] In a specific embodiment, the second thickness is 40 um, but is not limited thereto.

[0115] It can be understood that the first thickness and the second thickness can be adjusted according to actual needs.

[0116] In the embodiments of the present application, the optical properties of the phase difference film are adjusted by controlling the composition and ratio of the raw materials and the thickness of the prepared phase difference film, so that the in-plane phase difference (Ro) and the phase difference in the thickness direction (Rth) of the prepared phase difference film meet the requirements of the aforementioned embodiments, so that the prepared phase difference film can be applied to polarizers or display devices to improve the yellowish color and light leakage problems of the display device in the dark state when viewed from the side.

[0117] like Figure 3 As shown, the embodiment of the present application further provides a polarizer 1, which includes a polarizing layer 2, a protective layer 3 and the phase difference film 4 described in the above embodiment, wherein the phase difference film 4 is located on a side of the polarizing layer 2 away from the protective layer 3.

[0118] In some embodiments, the polarizer 1 further includes a pressure sensitive adhesive (PSA) layer 5 located on the side of the phase difference film 4 away from the polarizing layer 2, a release film 6 located on the side of the pressure sensitive adhesive layer 5 away from the polarizing layer 2, and a removable protective film 7 located on the side of the protective layer 3 away from the polarizing layer 2.

[0119] It can be understood that the polarizer 1 provided with the release film 6 and the tearable protective film 7 is a finished polarizer product. When the polarizer 1 is applied to a display device, the release film 6 and the tearable protective film 7 need to be torn off.

[0120] In a specific embodiment, the material of the polarizing layer 2 includes polyvinyl alcohol (PVA), but is not limited thereto.

[0121] In some embodiments, the material of the protection layer 3 includes triacetyl cellulose TAC, polymethyl methacrylate PMMA and polyethylene terephthalate (PET), but is not limited thereto.

[0122] In some embodiments, the preparation process of the polarizer 1 is as follows: the phase difference film obtained in the above-mentioned embodiment and the polarizing layer (such as PVA film) that has undergone processes such as washing, swelling, dyeing, stretching, fixing and drying, and the protective layer (such as PET, PMMA, TAC) are three-layered to obtain a polarizer substrate, the pressure-sensitive adhesive is coated on the PET film with a release agent, and then heated at a temperature of 80 to 120° C. for 1 to 5 minutes and then bonded together with the polarizer substrate to form the polarizer.

[0123] It can be understood that the PET film with the release agent is the release film 6 , and the pressure-sensitive adhesive is formed between the polarizing substrate and the release film to form a pressure-sensitive adhesive layer 5 .

[0124] Of course, other optical film layers may also be provided in the polarizer 1, and this application does not limit this.

[0125] In the embodiments of the present application, the polarizer contains the phase difference film described in the aforementioned embodiments, so that when the polarizer is applied to a display device, especially to a liquid crystal display device in FFS mode or IPS mode, the problem of yellowishness and light leakage in the dark state when viewed from the side of the display device can be improved.

[0126] like Figure 4 As shown, an embodiment of the present application further provides a display device 10 , which includes a display module 8 and the polarizer 1 described in the aforementioned embodiment, wherein the polarizer 1 is at least located on the light emitting side 9 of the display module 8 .

[0127] In some embodiments, the display module 8 is a liquid crystal display module, and the corresponding display device 10 is a liquid crystal display device.

[0128] In a specific embodiment, the display device 10 is a liquid crystal display device in FFS mode or IPS mode, but is not limited thereto.

[0129] It can be understood that the polarizer 1 located on the light-emitting side 9 of the display module 8 is an upper polarizer.

[0130] In some embodiments, the display device 10 further includes a backlight module (not shown) located at the back of the display module 8, and the polarizer 1 is also located between the display module 8 and the backlight module to serve as a lower polarizer.

[0131] Specifically, the embodiments of the present application do not limit the structures of the display module and the backlight module.

[0132] In the embodiment of the present application, since the display device contains the phase difference film described in the above embodiment, the problems of yellowish color and light leakage in the dark state when viewed from the side of the display device can be effectively improved.

[0133] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0134] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0135] The embodiments, implementation methods and related technical features of the present application can be combined and replaced with each other without conflict.

[0136] The above are only preferred embodiments of the present application and do not constitute any form of limitation to the present application. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A phase difference film, characterized in that: The phase difference film satisfies the optical properties expressed by formula (1) or formula (2): Rth(450) / Rth(550)>2 (1); Rth(450) / Rth(550)<-1 (2); In the formula, Rth(450) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 450 nanometers, and Rth(550) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 550 nanometers.

2. The phase difference film according to claim 1, characterized in that: The phase difference film also satisfies the optical properties expressed by formula (3) to formula (6): -10nm<Ro(450)<15nm (3); -20nm<Rth(450)<10nm (4); -20nm<Rth(550)<20nm (5); -20nm<Rth(650)<20nm (6); In the formula, Ro(450) represents the in-plane phase difference at a wavelength of 450 nanometers, and Rth(650) represents the phase difference along the thickness direction of the phase difference film at a wavelength of 650 nanometers.

3. The phase difference film according to claim 2, characterized in that: The phase difference film also satisfies the optical properties represented by the formula (1) and the following formulas (7) and (8): 0<Rth(450)<Rth(550)<Rth(650) (7); 2nm<Ro(450)<15nm (8).

4. The phase difference film according to claim 2, characterized in that: The phase difference film also satisfies the optical properties expressed by the formula (2) and the following formula (9): Rth(450)<0<Rth(550)<Rth(650) (9).

5. The phase difference film according to claim 2, characterized in that: The phase difference film also satisfies the optical properties represented by the following formulas (10), (11) and (12): Rth(450)<0<Rth(650)<Rth(550) (10); Rth(450) / Rth(550)<-1.5 (11); -2.5nm<Ro(450)<15nm (12).

6. The phase difference film according to any one of claims 1 to 5, characterized in that: The material of the phase difference film includes a phase difference adjusting agent, and the phase difference adjusting agent is selected from at least one of polyurethane, polyvinyl chloride, chlorinated polyvinyl chloride, polypropylene, chlorinated polypropylene and polyethylene.

7. The phase difference film according to claim 6, characterized in that: The material of the phase difference film further includes a substrate, and the substrate is selected from polymethyl methacrylate or triacetyl cellulose.

8. The phase difference film according to claim 7, characterized in that: In the material of the phase difference film, when the weight proportion of the phase difference film is 100 parts, the weight proportion of the substrate is greater than or equal to 90 parts and less than 100 parts, and the weight proportion of the phase difference adjusting agent is greater than or equal to 0.9 parts and less than or equal to 7.5 parts.

9. A polarizer, characterized in that: The invention comprises a polarizing layer, a protective layer and the phase difference film according to any one of claims 1 to 8, wherein the phase difference film is located on a side of the polarizing layer away from the protective layer.

10. A display device, characterized in that: It comprises a display module and the polarizer as claimed in claim 9, wherein the polarizer is at least located on the light-emitting side of the display module.

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